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I would like one also Thank you Krzysztof Bak sgbak@cyf-kr.edu.pl Użytkownik Judith Harris napisał: > I would like a copy. I am a vert person but this sounds fascinating. > > Thanks, > > Judith > > judith harris > emerita professor > university of colorado museum > p.o. box 278 > chama, nm 87520 > harrisj@valornet.com > > > On Sep 21, 2006, at 2:37 AM, Jean Guex wrote: > >> To anyone interested I can send the following paper in PDF form: >> >> "Reinitialization of evolutionary clocks during sublethal >> environmental stress in some invertebrates." >> >> Abstract >> This paper describes the influence of high environmental stress on >> evolutionary trends in some selected Mesozoic ammonite lineages and >> some protists. During extinction periods, many ammonoids are affected >> by drastic simplifications of their shell geometry, ornamentation and >> suture line. We observe that relatively tightly coiled ammonites can >> give rise to highly evolute forms or uncoiled heteromorphs with >> simple ornamentation and almost ceratitic suture line - a phenomenon >> called "proteromorphosis". Such simplifications often correspond to a >> reappearance of ancestral geometries (primitive ornamentation, >> evolute coiling or uncoiling) which suggest that the evolutionary >> clock of these organisms can be reinitialized by extreme, sublethal, >> environmental stress such as giant volcanism (including its >> consequences on diverse pollutions and on climatic changes) and major >> regressive events. >> >> >> >> > > >
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